Power supply is an utmost essential tool for an electronic lab. It comes in handy for powering up various applications and circuits. However a fixed voltage, fixed current power supply is sufficient for basic needs but a variable one is good to have because different circuits and components operate at different voltages and consumes different current.
Also if the power supply boosts additional features like on board voltage and current display, it comes in handy as one can know the exact voltage at the output terminals and also the current drawn by the load.Build a Simple Power Supply
But in the electronic market, those power supplies are not economic are meant for industrial purpose. Here in this article I present an economical and cost effective yet efficient variable bench power supply that is capable of providing 1.
It also displays the voltage on the output terminals and also the current and instantaneous power drawn by the load on an on board LCD display. Not only this one can connect this power supply to his personal computer via the serial port and can see the voltage, current and power drawn by the load graphically. The project is portable and simple to build that even a newcomer can build this power supply with ease and add into his lab.
The project uses component that are easily and cheaply available. The project is composed of two modules, one is main power module that consists of linear voltage regulators with rectification and filtering circuitry for supply generation and regulation while the other is composed of a micro controller which is used to sense and display the current and voltage across the variable supply channel.
The second section only provides an additional functionality of displaying current and voltage, however one can build the power supply even skipping the second section leaving it functional but without the display feature. Actually this version 2,I have already build one which was later modified with new features.
Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. The block diagram is divided into two parts, one for each section : The main power section is the one which is used to derive a regulated DC voltage from the mains V AC input. The diagram is divided into four sections. This uses a step down transformer. Then second section is the rectification section which rectifies the AC component of the signal of its input.
It uses a bridge rectifier. Then the signal is passed onto the third section which is the filtering section which consists of capacitors which act as a first order low pass filter and further smooths the signal. After this stage, we get a smoothened DC voltage which is ready to be interfaced to the next section which is the regulator section.
Now as we have three channels for our supply output that is one variable supply channel and two others are fixed ones, so the regulator section is further divided into three sections one for each channel. The two regulator sections comprise of a fixed linear voltage regulator while the third one consists of a variable linear voltage regulator.
Thus at the end, we get our three channels of power supply which goes to the output terminals. The block diagram for the second version 1 section is given below. This is the interface and display section which senses the current and voltage on the variable supply channel and gives off the readings to the LCD display and computer. It consists of a voltage divider section and a series shunt arrangement at the variable supply channel for sensing the voltage across the terminals and current through load respectively.
A non-inverting amplifier is used after the shunt arrangement to amplify the voltage drop across the shunt resistor. The outputs of the voltage divider network and the non-inverting amplifier goes to analog-to-digital converter inputs of a microcontroller in the next stage which converts these real time analog data into digital ones so that it can be processed in the microcontroller, interpreted and sent off to the serial interface and display section.
Two buttons are provided to act as inputs and a buzzer is there to give audio messages. Version 2 description in addition to version 1 : Version 2 of this power section is similar to the version 1, rather only some minor improvements were made like we have increased two more uf,50V filtering capacitors, and added nf ceramic caps after LM and LM for functional stability purpose. So we have included a series array of 1N or any general purpose diode to make an appropriate voltage drop before it goes to the two fixed voltage regulators.
So after diode D18, we will get a nominal voltage of 16v which feed the LM and a nominal voltage of 10v after D26 which feeds the LMOne of the more popular projects for beginners in electronics is a power supply.
The design goals for this project were to build a small and compact unit using mostly salvaged and recycled components, with all through-hole circuitry. After rummaging through his parts, he found what he was looking for: a TIP power transistor, a neat enclosure that could double as a heatsink and an AD voltage reference.
This is just a one-off project, but the results are fantastic. This is a very small, very capable power supply that does everything [Tron] needs. What more could you want in a benchtop power supply? Cute, but it has a couple of beginner errors in it.
Since the LM input range does not cover the positive rail, he used a divider, which without matched resistors is quite bad for common mode rejection.
Also learned this lesson the hard way. Extra: it becomes very slow because of the triple slow op-amps which control the transistor in case of current limitation. This is also why it required so much output capacitance, which is not desirable for such a small supply. I would recommend instead to adapt his parts to the electronics lab power supply design, even using the fancy reference instead of the one with zenner diode.
Still, I admire the project, but has a few things to fix. This may not be a problem for you, but many parts these days require a very low supply voltage. Some even less than 1v.
So I was a bit upset that after watching several hours of his series he threw away that requirement. He did a lot few weird things in there, like using the expensive LT almost as a simple tranzistor just to try and reach 0V. A negative supply would have fixed things easier and end up allowing real zero output note his will still not output zero in case of an overload.
My school had a design like this and we where not allowed to change the design, flowers are red, etc. When switching off the supply, unplugging it, something else tripping a mains breaker or in case of power loss, the capacitors of this -3V reference would run out first, resulting in a 3V jump of the reference and also in the power supply output.
This was 20 years ago when my ARM computers needed a 1. The rest wast not that bad, but this single feature made the whole supply too dangerous to use. LTC parts are expensive and sometimes hard to obtain in smaller prototype-level quantities. I would ask [Tron] for these files to be included, but alas it seems I have to sign-up for a separate hackaday. I was talking about Dave doing weird things in his design, not Tron LT spice is a good tool.
Plus, many manufacturers offer spice models for their parts, even though they are not the easiest thing to find. Nice, clean, simple. This looks like a sweet build.
This site uses Akismet to reduce spam. Learn how your comment data is processed. By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies. Learn more. Report comment. Less than 2 min. Leave a Reply Cancel reply. Search Search for:. Hackaday Links: April 12, 14 Comments.Only 6 left in stock - order soon. I had a really great time putting this kit together and it's a good power supply for the price.
I should also mention that it also has other functionality, a continuity checker - which emits a tone much like a DVM does and a logic tester which I have yet to figure out how to use. It's very cool looking when it's fully assembled too - the photo is a dead on representation of what you can expect after you finish assembly. Add to cart. In Stock. I happen to be a tech journalist and reviewer.
For a while now, I'd been needing a variable power supply to help with doing some benchmarks for various devices, but I didn't know very much about them. Fortunately, I got the opportunity to test this unit, and I'm definitely sold. Electricity is deceptively complex. The average consumer doesn't put much thought into the power with which they're supplying their devices; they just know that when they plug a device into a wall outlet, the device charges.
But every device has different power needs. For some, anything above the maximum power level could fry the device's battery and circuits. Plus, I've read horror stories about different USB cables being faulty and getting fried by even just the amount of current that comes from a standard wall outlet.
The first thing that struck me about this variable DC power supply, made by Eventek, was Okay, there are a number of reviews here on Amazon that point out the cons of this unit.
Allow me to say this about how the regulators are installed on the heatsink. The only way to keep costs down as well as build assembly simple, is to use this method. Other options would require active cooling with a noisy fan and internal heatsinks with pin guides for the PCB which for people new to kits like this and Elenco designs this series for studentswould increase difficulty. If you've never loosely stuck a TO pack to a pin guided heatsink with thermal greasethen tried to tighten things up and solder in place, then finish screwing it in place before and that would have to be done four times in this kitthen this is a much simpler solution.
All things considered I would Currently unavailable. High quality,well built. I'm going to use this as a benchtop adjustable power supply.Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. Before you start opening the case of ATX power supply first keep the power supply unplugged to discharge those high voltage capacitors.
Then open the case of ATX power supply and clean the internal electronics with a brush or blower. Now we first need to check if the power supply is in working condition. To check that take pin connector and connect 14th pin i. If power supply's fan starts then it is in working condition. Now you can trim down the wires to an appropriate length because we don't need connectors. Once done Sort the wires according to color.
Now drill holes for banana Connectors Binding post and attach them, Make sure they are tight or else they can short something in future.
Now strip all the wires and solder them in a group according to their colour. Now solder the entire bunch to the binding posts. Make sure to leave 2 Black wires,1 Red and 1 Green wire. To make sure our Power supply output is stable we need to add a dummy load, add a 5 Ohm 10w resistor to it.
I don't have a 10W so I'm using two 10 Ohm 5W in parallel. Now solder Red and Black Wire across it. Don't forget to cover it with some tape, and place the resistor in the power supply case.
You can add a Switch otherwise. Note that you can get some useful voltages from working between the differing voltage rails. I miss good serial ports! Reply 2 months ago. I built one, using a ohm 5W sandblock and it runs fine. To anyone who makes batt charger if charging flatter batt use headlight globe in series to limit current, or could burn out supply.
Don,t ask! Eg 12v batt, use 12v halogen bulb in pos line W.There are many types of power supply. Most are designed to convert high voltage AC mains electricity to a suitable low voltage supply for electronics circuits and other devices. A power supply can by broken down into a series of blocks, each of which performs a particular function. Each of the blocks is described in more detail below: Transformer - steps down high voltage AC mains to low voltage AC. Smoothing - smooths the DC from varying greatly to a small ripple.
Regulator - eliminates ripple by setting DC output to a fixed voltage. All Rights Reserved. This is called a 'dual supply' because it is like two ordinary supplies connected together as shown in the diagram. It is not suitable for electronic circuits unless they include a rectifier and a smoothing capacitor.
It is not suitable for electronic circuits unless they include a smoothing capacitor. It is suitable for most electronic circuits. It is suitable for all electronic circuits. Transformers convert AC electricity from one voltage to another with little loss of power. Transformers work only with AC and this is one of the reasons why mains electricity is AC. Step-up transformers increase voltage, step-down transformers reduce voltage.
Most power supplies use a step-down transformer to reduce the dangerously high mains voltage V in UK to a safer low voltage. The input coil is called the primary and the output coil is called the secondary. There is no electrical connection between the two coils, instead they are linked by an alternating magnetic field created in the soft-iron core of the transformer.
The two lines in the middle of the circuit symbol represent the core. Transformers waste very little power so the power out is almost equal to the power in.
Note that as voltage is stepped down current is stepped up. The ratio of the number of turns on each coil, called the turns ratio, determines the ratio of the voltages.This is a small bench power supply that I made some time ago, and because I was very busy I couldn't do the instructable for it.
I do apologise for taking so long, I hope it was worth the wait :. After making my Mini Adjustable Power Supply I was very happy with it, but I was missing a more accurate control of the voltage and current. So I decided to make this slightly bigger but still small bench power supply. The heart of the unit is basically the same as on the other power supply. It is based on the LMS. This IC can handle up to 3A with a good heat sink.
I would use it only for 2A to be on the safe side. Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. Here is a list of materials and tools I used for this project. Many of them can be replaced with other components that you may have already, but I would definitely use an aluminium enclosure, as I used it as a heat-sink as well. I have tried to find the cheapest components, but double check that the price has not changed, you may find it cheaper somewhere else.
The rest of the components are only necessary if you want to have LEDs to let you know if you limiting the current or the voltage, and to let you know if the output is set to on. One should fit inside the other and the inner one has to be big enough so the aluminium enclosure fits inside.
See step 2 for photos. They also need to be heat resistant. After taking measurements of the enclosure and all the components, I designed the layout of the front of the unit with Photoshop. I added the file so you can modify it to your needs. If you are designing it in another enclosure, just make sure you take into account what's inside the enclosure and fitting points.
Place the front of the aluminium enclosure on top of the photo paper, printed side facing the aluminium. Use the iron to heat as evenly as you can the other side while applying pressure. Do this for about two minutes, or when you see the back looking like the one on the photo.
Wait for it to cool down, and peel the paper off. If everything when well your design will be left on the enclosure. Inspect the printed area to see bright spots, and paint them with nail polish. Anything that is not covered will be etched. Use tape to protect the rest of the front of the enclosure so you don't damage it with the etching solution. Wear gloves and eye protection when handling the etching solution.
Use the solution only in a well ventilated area. The etching solution will stain yourself as well as pretty much everything it touches, and it will damage anything metal, especially be careful with the sink if is the metal type, when washing the enclosure. Pour some of the etching solution in the smaller container and leave for a few minutes to warm up.
Place the front of the box in there.A bench power supply is an extremely handy bit of kit to have around for electronics hobbyists, but they can be expensive when purchased from the market. In this Instructable, I will show you, how to make a variable lab bench power supply with a limited budget.
It is a great DIY project for beginners as well as any one interested in Electronics. The main objective of the project is to learn how a linear power supply unit works. This is a high quality stabilized voltage supply with which the voltage can be regulated continuously, and the range in which to regulate the voltage is V.
It even contains a current limit circuit which can effectively control the output current from 2mA to 3A with the ability to regulate the current continuously, and this unique feature makes this device an indispensably powerful tool in the circuit lab.
Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. Before heading in to the making process, you should know the basic components of a Linear Power Supply. Transformer: The transformer changes the ac mains voltage to a desired value. It is used to step down the voltage. This also serves to isolate the power supply from the mains input for safety. The bridge rectifier converts AC into DC. But this is not we want, we want a pure ripple free DC waveform.
The filter circuit is used for smoothing out the ac variations ripple from the rectified voltage. Large reservoir capacitors are used for this. Linear regulator: The output voltage or current will fluctuate when there is change in the input from ac mains or due to change in load current at the output of power supply. This problem can be eliminated by using a voltage regulator. It will maintain the output constant even when changes at the input or any other changes occur.
Input high voltage AC going into a transformer which usually steps down the high voltage AC from mains to low voltage AC required for our application.
For designing the Power Supply,the transformer secondary voltage is selected by considering the the output voltage of the power supply, losses in the diode bridge and the linear regulator. A typical waveform of 24V transformer is shown above.
In general we allow about 2V - 3V drop for the bridge rectifier configuration. So the transformer secondary voltage can be calculated as below. The nearest voltage rating transformer available in the market is 24V. Note : The above calculation is a rough estimation to buy a transformer.
For accurate calculation you have consider voltage drop across diodes,voltage drop of the regulator, ripple voltage and rectifier efficiency also.
The rectifier bridge convert an alternating voltage or current into corresponding direct Current DC quantity. The input to a rectifier is ac whereas its output is unidirectional pulsating DC.